Air regulating means for liquid-fuel furnaces



Oct 1934- H. c. GRANT, JR 1,976,680

AIR REGULATING MEANS FOR LIQUID FUEL FURNACES Filed July 1. 1952 2 Sheets -Shet 1 INVENTOR HGURE BY fiARRY CAMPBELL GRA/WCJR.

ATTORNEY Oct. 9, 1934. H. c GRANT JR v 1,976,680

AIR REGULATING MEANS FOR LIQUID FUEL FURNACES Filed July 1, 1952 2 Sheets-Sheet 2 4 75 76 FIGURE 3 FIGURE 2 L4-5 FIGURE 4 FIGURE 5 INVENTOR HARRY CAMPBELL GRANZJR.

ATTORNEY Patented Dot. 9, 1934 AIR REGU LATING MEANS FOR LIQUID-FUEL FURNACES Harry Campbell Grant, Jr., New York, N. Y., as-

signor to Walter Kiddo & Company, Inc., New ,York, N. Y., a corporation of New York Application July 1, 1932, Serial No. 620,430

20 Claims. (01. 236-15) This invention relates to means for varying the volume of air. for combustion purposes supplied to liquid-fuel furnaces and the like through the medium of automatic control means actuated by the pressure of the fuel, so that proportionate quantities of fuel and air are introduced into a furnace under all variations of heat production found desirable.

It is Well-known in combustion practice that,

for the maintenance of the highest possible efllciency it is necessary that the exact quantity of air be supplied to a furnace to allow for the complete combustion of the fuel being delivered.

If less than the required quantity of air is supplied, incomplete combustion results, together with smoking. If more than the required amount of air is supplied, combustion will probably be complete but will result in considerable loss of heat up the furnace stack.

It is accordingly the primary purpose of the present invention to maintain the highest possible combustion efliciency of liquid-fuel furnaces, the invention having been developed with particular attention to marine practice to which it is particularly adaptable and in connection with which it has already encountered considerable success.

More specifically, the present invention constitutes an improvement both in the invention shown and described in Letters Patent of the United States No. 1,685,031, dated September 18th, 1928 and granted to Barton H. Noland,

and in the invention shown and described in the copending application of Barton H. Noland, Serial No. 614,707, filed June 1st, 1932.

As distinguished from the prior patent and prior application referred to, wherein a balancing mechanism controlled by the variable pressuresv of fuel and air-itself directly controls 40 the supply of steam to the air delivery control means of a furnace, the present invention contemplates the use of electrically operated means for translating the controlling effect of the balancing mechanism into control of the supply of steam to the air delivery control means.

It is accordingly an object of the present invention to provide a regulating mechanism 'for maintaining a balanced condition between the quantities of fuel and air delivered to a furnace, said regulating mechanism comprising electrically operated means for translating the controlling effect of a balancing mechanism into operations required to produce the desired balanced condition between the quantities of fuel and air.

It is another object of the invention to provide a steam supply valve which is not only automatically operated to effect desired opening or closing thereof, but which is provided with means for preventing any tendency of the valve to be operated beyond desired limiting open and closed positions.

A further object is to provide a steam supply valve for the air delivery control means of a furnace which can be opened quickly or slowly to take care of sudden changes in the demand for air under widely varying operating conditions.

- A still further object is to provide means for preventing arcing and chattering of the controlling contact of the controlling balancing mechanism. 7

Another object of the invention is to provide indicating means for indicating whether the supply of air from the air delivery control means is increasing or decreasing at any given time.

Another object is to provide means for testing, at any time, the operating condition of the regulating mechanism.

Further objects of the invention will be apparent as the same is described more fully in connection with the accompanying drawings, wherein:

Figure 1 is a combined diagrammatic representation and wiring diagram of one embodi- 35 ment of my invention.

Figure 2 is a view, partly in section, of the steam supply valve limit switch assembly.

Figure 3 is a view, partly in section, taken at right angles to the view in Figure 2, the upper element of Figure 2 being sectioned centrally thereof.

Figure 4 is a view in elevation of the arrangement for .eliminating arcing and chattering of the controlling contacts of the controlling balancing mechanism.

Figure 5 is a sectional View, taken on line 5-5 and looking in the direction of the arrows,

the supporting means of the upper and lower limit contacts, however, not being sectioned.

Referring to Figure 1, I have illustrated at A a furnace having an induced draft stack B and an air delivery duct C, the delivery of air to the latter being effected by a blower D controlled by a prime mover E in turn subject to the controlling effect of a steam supply valve F. The reference character G represents a source of steam, while H represents the fuel supply to the furnace A. r

At 1 is shown a balance arm having a fulcrum at 2 and having suspended therefrom two air containers 3 and 4. These air containers are arranged to rise and fall within tanks 5 and 6 containing an air-sealing liquid, such as water. The interior of the air container 3 is connected by means ofa pipe line 7 with'the forced draft duct C, while the interior of the air container 4 is connected'by means of a pipe line 8 with the induced draft stack B. At 9 is shown an expansible bellows-like member which is connected by .a pipe line 10 with the fuel supply H and which is adapted to expand and contract upon variations in the pressure of the fuel, the movements of the bellows-like member ,being transmitted, against the compressive force of a spring 11, to an arm 12, pivoted at 13, and connected by a link 14 with a carriage 15 supporting a number of weights 16 and adapted to be moved along the balance arm' 1 with the aid of a roller 1'7,

The arrangement as just described, enables a balanced condition to be maintained by the balance arm between the variable pressures of the fuel and air delivered to the furnace and, while this arrangement in itself forms no part of the present invention, it is the purpose of the present invention to translate the controlling effect of the balance arml into the operations necessary to actuate the blower steam supply valve F so as to effect the desired balanced condition between the quantities of fuel and air delivered to the furnace.

The reference numeral 18 represents a contact supported on the balance arm 1 and adapted to rise and fall with the balance arm between contacts 19 and 20 arranged to define upper and lower limiting positions 01 the balance arm. The contact 18 is electrically connected, as by a flexible connection 21, through a manually operable switch 22, wire 23, wire 24, wire 25,

fuse 26, and one side of the double pole switch 27 to the positive side of a source of electrical energy. The upper contact 19 is connected by wires 28 and 29 with the. coil of an electromagnet 30, which in turn is connected with the negative side of the source of electrical energy through wire 31, conducting piece 32 and con ducting piece 33 of a limit switch assembly (shown' in Figure 2), wires 34, 35 and 36, fuse 37, and the other side of the double pole switch 2'7. The lower contact 20 is similarly connected to the negative side of the source of electrical energy by wires 38 and 39, thecoil of an electromagnet 40, wire 41, conducting piece 42 and conducting piece 33 of the limit switch assembly, wires 34. 35 and 36,-fuse 37,,and one side of the double pole switch 27.

In practice, the electro-magnets 40 and 30 are arranged on a single support and control a single armature pivoted intermediate of the electro-magnets and extending over the cores of both electro-magnets, as will be described hereinafter in further detail in connection with Figure 4. For the present it will be suflicient to note that the energization of the electro-magnet 40 effects the making of contact at 43 and 44, while the energization of the electro-magnet 30 effects the making of contact at 45 and 46,-

the movable contact elements 47, 48, 49 and 50 being mounted on but electrically insulated from the armatures It will of course be noted that the movable contacts 4'land 48 are electrically connected while the movable contacts 49 and 50 are similarly electrically connected.

The fixed contacts 43, 44, 45 and 46 are electrical motor 54 arranged to rotate the valve stem 55 in either direction through the reduction gear assembly 56, the armature leads for the motor 54 being shown at A1, and A2, while the field leads are shown at F1 and-Fa.

Let it now be assumed that the balance arm is in its balanced position, denoting a desired balanced condition between the quantities of fuel and air supplied to the furnace, with the contact 18 floating midway between thecontacts 19 and 20. Let it then be assumed that a change in the pressure of the fuel supplied to the furnace occurs to such an extent as to move the balance arm from its balanced position and cause the contact 18 of the balance arm to make contact at 19 or 20. Further assuming that the pressure of the fuel has increased, the position of the weights 16 will be shifted toward the left along the balance arm 1, thereby causing con-.

tact to be made at 20, whereupon connection is established from the positive side of the source of electrical energy, through one side of the double pole switch 27, through fuse 26, wire 25, wire 24, wire 23, switch 22, connection 21, contact 18-20, wire 38, wire 39, electro-magnet 40, wire 41, conducting piece 42 and conducting piece 33 of the limit switch assembly, wires 34, 35 and 36, fuse 37 and the other side of the double pole switch 27 to the negative side of the source of electrical energy. The electromagnet 40 is consequently energized and attracts its end of the single armature, closing the contacts 434'7 and 44-49. Connection is therefore established from the positive side of the supply through wire 25, wire 57, junction 58, connector 59, contact 47-43, resistance 52, contact 46, wire 60, armature lead A2, through the armature of the motor 54, armature lead A1, wire .61, contact 44-49, connector 62, junction 63,

and wires 64, 65, 66 and 36 to the negative side of the supply. In view of the fact that the field coil of the motor is connected from the positive side of the supply through wire 25, wire 24, wire 67, field coil lead F1, through the field coil of the motor 54, field coil lead F2, and wires 68, 35 and 36 to the negative side of the supply, thearmature of the motor 54 will rotate in a direction to transmit, through the reduction gear assembly 56, an opening motion to the valve stem 55 of the blower control valve F, causing the prime mover E to speed up the motion of the blower D until sufficient pressure is built up in the air delivery duct C to cause the pressure transmitted through the pipe line 7 to raise the air container 3 and the balance arm 1 to the normal balanced position, whereupon the contact 18-20 is broken, the electrocircuit of the motor armature is interrupted,

resulting in the stopping of the motor with the blower steam supply valve F in the desired balance-maintaining position. a

With the arrangement as just described, the

close adjustment of the speed of the blower D,

' but the rate at which this valve changes its setting toreadjust the forced draft following some cause'requiring such an adjustment is sufficiently rapid for all conditions excepting in some cases when a great number of fires is suddenly cut in, in which case the opening of many dampers suddenly will cause the forced draft to drop and may allow smoking while the blower is speeding up to bring the forced draft back to normal. As this is a usual occurrence in marine maneuvering, and when it is known that fires are to be cut in and out rapidly, the switch 53 should be closed, so as to short-circuit the speed-controllingresistance 52. This will cause the blower valve F to open at a speed considerably greater than normal and usually at' such a high rate that the forced draft will become excessive before the regulating mechanism can stop the valve. The valve will immediately reverse, however, and slowly bring the draft down to normal, thus preventing smoking while maneuvering. In order to prevent this excessive draft when conditions are fairly constant, as at sea, the switch, 53 should normally be left open.

The method of operation of the apparatus for re-establishing the balanced condition between the quantities of fuel and air upon an increase in the pressure of the fuel having been described, let it now be assumed that the pressure of the fuel decreases with consequent movement of the weights 16 toward the right along the balance arm 1, thereby causing contact to be made at 19, whereupon connection is established from the positive side of the source of electrical energy, through one side of the double pole switch 27, through fuse .26,- wire 25, wire '24, wire 23, switch 22, connection 21, contact 18-19, wire 28, wire 29, electro-magnet 30, wire 31, conducting piece 32 and conducting piece 33 of the limit switch assembly, wires 34, 35 and 36, fuse 37, and the other side of the double pole switch 27 to the negative side of the source of electrical energy. The electro-magnet 30 is consequently energized and attracts its endrof the single armature, closing the contactsv48 and 46 50. Connection is therefore established from the positive side of the supply through wire 25, wire 57, junction 58, connector 69, contact 4845, resistance 51, contact 44, wire 61, armature lead A1, through the armature of the motor 54, armature lead A2, wire 60, contact 46-50, connector 70, junctionGB, and wires 64, 65, 66 and 36 to the negative side of the supply. In view of the fact that the field coil of the motor is connected across the source of electrical energyin the same manner as already described, the armature of the motor '54 will rotate in the opposite direction to that previously described and will transmit through the reduction gear assembly 56, a closing motion to the valve stem of the blower valve F, causing the prime mover E to slow down the motion of the blower D until the pressure in the ,air delivery -...duct. Cis reduced sufiiciently to cause the pres- .xa sure transmitted through the pipe line 7 to permit' th'e'lowering of the air container 3 and the balanceflarm '1 to the normal balanced position,

whereupon the contact 1819 is broken, the electro-magnet 30 is de-energized, and the energizing circuit of the motor armature is inter- I rupted, resulting in the stopping of the motor with the blower steam supply valve F in the desired balance-maintaining position.

It will have been noted that the resistances 52 and.51 are speed-controlling resistances in series with the armature of the motor 54 upon opening and closing movements respectively, and that in the specific embodiment of the invention herein-described, means has been shown to short-circuit the resistance 52 so as to permit an opening of the blower steam supply valve F more rapidly than is normally required.

Reference has been made in the preceding description .to the use of a limit switch assembly, the construction and purpose of which can best be understood in connection with Figure 2, it being kept in mind, however, that the contacts 72 and 71 (Figure 2) are normally closed and are in the energizing circuits of the electromagnets 40 a11 d30 respectively. The purpose of the limit switch assembly is to prevent any tendency of the valve to be operated beyond desired limiting open and closed positions.

Referring now to Figure 2, it will be noted that the limit switch assembly comprises a. base 73 of insulating material, said base being provided with recesses 74 serving to receive pro-' jections of conducting pieces 42 and 32, which are pivoted in the recesses on pins 75. A conducting piece 33 is suitably mounted on the base 73 by means of a conducting screw 76, the conducting piece 33 being arranged to contact at 72 and 71 with the conducting. pieces 42 and 32. The base 73 is also provided with openings 7'7 to receive commercially obtainable springpressed button assemblies 78 and 79, these assemblies serving to rotate the conducting pieces of Figure 1 will now be readily understood since similar reference numerals have been employed in both figures wherever possible. The operation of the limit switch assembly is effected by means of a slide block 80 provided with motion transmitting screw threads 81 which engage cooperating screw threads on a shaft 55 which,

when the limit switch assembly is employed in connection with the invention of Figure 1, is

the connection between the reduction gear assembly 56 and the blower steam supply valve F. The slide block 80 is provided with 2. depending projection 82 lying between the conducting pieces 42' and 32. The slide block 80 as at 83 for the reception of bars 84 which are supported in any suitable manner, as shown in Figure 1 for example. By reason of this arrangement of parts, rotation of the shaft 55 will cause the slide block 80 to slide along the bars 84 and will cause the projection 82 to engage either the conducting piece 42 or the conducting piece 32, breaking the contact at either 72 or 71,.depending upon the direction of rotation of the shaft 55. The various parts of thelimit switch assembly are so proportioned that, when the steam supply valve is completely closed, the limit switch toward the valve, i. e., the conducting piece 32, opens the contact 71, thus opening the energizing circuit of the electro-magnet 30 and preventing the valve from attempting to close further. Conversely, the limit switch toward. the motor, i. e., the conducting piece 42, when engaged by the slide block to is grooved open the contact 72, opens the energizing circuit of the electro-magnet 40 and prevents the valve from opening further.

Reference has also been made inthe preceding description to a specific arrangement of the electro-magnets 40 and 30 and the contacts associated therewith. As this mounting of the electro-magnets also involves a novel feature for preventing arcing and chattering of the contacts 19 and 20 when contact is made with either one or the other by the normally floating contact 18, the mounting will now be described in detail in connection with Figures 4 and 5, wherein it will be noted that the electro-magnets 40 and 30 are mounted upon an insulating base having standards 86 and 87 for supporting a shaft 88 to which is secured, as by means of a pin 89, an armature 90 which extends over the cores of the two electro-magnets, the armature being pivoted intermediate the axes of the electro-magnets. The mounting of the contacts 44 and 49, as described in connection with Figure 1, is clearly shown in Figure 4, the contact 49 being insulated from the armature 90 by .the insulating block 91. The mounting of the contacts 46 and 50, 43 and 47, and 45, and 48, while not specifically shown, is similar to the mounting of the contacts 44 and 49. It will be noted that the junction points 58 and 63 and the connectors 62 and '70 have been indicated .so as to show their relationship to Figure 1.

In order to maintain the armature 90 in a neutral position with respect tothe cores of the two electro-magnets, a spring leaf 92 is provided, resting at one end within a slot 93 on a projection 94 of a collar 95 suitably secured to the shaft 88, as by a pin 96. The other end of the spring leaf 92 rests between projections 97 on a bar 98 secured to the insulating block 85. The various parts are so proportioned that the spring leaf 92 tends to retain the armature 90 in a neutral position with respect to the cores of the two electro-magnets, yielding sufficiently to permit the attraction of the armature by either electro-magnet, and returning the armature to its neutral position upon deenergization of the electro-magnets.

In order to prevent arcing and chattering of the contacts 19 and 20, as previously mentioned, these contacts are mounted, as shown, on an insulating block 99 which is suitably secured to the shaft 88, as by means of a flattened hole engaging a flattened portion 100 of the shaft 88; It will accordingly be noted that the contacts 19 and 20 are caused to rotate with the armature 90, and it is this simple construction which prevents arcing and chattering of the contacts 19 and 20 by reason of the engagement of either one or. the other of the contacts with the normally floating contact 18. Thus, on the assumption that the contact 18 on the, balance arm 1 moves downward into engagement with the contact 20, and keeping in mind that closing of the contact 18--2O results in the energization of the electro-magnet 40, it will be noted that the elect'ro-magnet 40 will pull down the left-hand I end of the armature 90, thus causing a counterclockwise rotation of the insulating block 99 and the contacts mounted thereon, whereby the contact 20 will snap up into definite engagement with the contact 18, thus preventing arcing and chattering such as might ensue from the initial engagement of the contacts under the influence of the balance arm'l. From what has been said in connection with the engagement of the contacts l8 and 20, it will readily be understood that initial engagement of the contacts 18 and 19 will result in energization of the electro-magnet 30 and the rotation of the contact 19 in a clockwise direction so as to bring it into definite non-arcing and non-chattering engagement with the contact 18.

.ergy to the switch-point 103 and to the contacts 104 and 105. It will of course be understood that breaking the connection to positive of the contact 18, discontinues the automatic operation of the regulating mechanism. It, now, the switch 106 is depressed so as to break contact at 104 and make contact at 102, the electromagnet 40 will be energized in the same manner as if contact had been made between, the contacts 18 and 20. Furthermore, if the switch 107 is depressed so as to break contact at 101, the electro-magnet 30 will be energized in the same manner as if contact had been made between the contacts 18 and 19. It will accordingly be seen that the switches 106 and 107 to-' gether with their associated contacts, constitute means for testing the operability of the regulating mechanism at any desired time. If the regulating circuit is in operative condition when the switch 106 is depressed, resulting in the energization of the electro-magnet 40 and the opening of the blower steam supply valve F, the special indicator 108, which may quite suitably be a green lamp, is energized by reason of its connection in a circuit from the positive side of the source of electrical energy, through 25 and 57, junction 58, connector 59, contact 47-43, wire 109, and wires 110, 66 and 36 to the negative side of the source of electrical energy. A similar indicator 111, which may quite suitably be a red lamp, is provided to indicate when the regulating circuit is in operative ,condition by reason of energization of the electro-magnet 30 under the influence of the switch 107.

At the same time the indicating lamps 108 and 111 serve to indicate whether the forced draft is being increased or reduced when subject to, the influence of the automatic regulating mechanism, a neutral or balanced condition being indicated by nonoperation of both of the indicators 108 and 111. Thus, with the lamp arrangement already described, a green light will show when the regulator is increasing the forced draft, while a red light will show when the regulator is reducing the forced draft.

will close the lower contacts 18 and 20 to in crease the forced draft upon a decrease in the induced draft, or upon a drop in the steam pressure (causing the blower to slow down), or upon an increase in the pressure of the fuel, orupon a decrease in the forced draft itself, due to the cutting in of more fires. Conversely, the regulatingmechanism will close the upper contacts- 18 and 19 to decrease the forced draft upon an increase'in the induced draft, or upon an increase in the steam pressure, or upon a decrease in the pressure of the fuel, or upon an increase in the forced draft itself, due to the cutting out of fires. 7

From the foregoing-description it will be apparent that I have made various substantial improvements in regulating mechanisms of the general type referred to. It is to be understood, however, that the present invention, while it has been described with specific reference to the accompanying drawings, is not .to be limited, save as defined in the appended claims.

- I claim:

1. In a regulating mechanism for maintaining a balanced condition between the quantities of fuel and air delivered to a furnace and embodying a beam balanced about'a fulcrum by the variable pressures of the fuel and the air, said ,beam exerting a controlling effect on the pressure of the air delivered to a furnace by relatively small movements of the beam on either side of its balanced position and between limiting positions, the combination of means for controlling the delivery of air to a furnace, an electrical circuit for controlling the last named means to cause it to effect an increase in the quantity of air delivered, a second electrical circuit for controlling said last named means to cause it to effect a decrease in the quantity of air delivered, two electrical contacts arranged to define upper and lower limiting positions of the beam, each contact being electrically connected with a different one of the two electrical circuits, and a contact on the beam arranged to float normally between the first mentioned contacts and adapted to effect energization of either one or the other of the two electrical circuits upon contacting with either one or the other of the first mentioned contacts, depending upon the direction of unbalance of the beam, so as to reestablish the balance of the beam and of the quantities of fuel and air delivered to the furnace.

2. In a regulating mechanism for maintaining a balanced condition between the quantities of fuel and'air delivered to a furnace and embodying a beam balanced about afulcrum by the variable pressures of the fuel and the air,

said beam exerting a controlling effect on the delivery means, a valve for controlling the supply of fluid to the prime mover, electrically operated means connected to the valve for effecting different degrees of opening and closing of the valve, an electrical circuit for controlling the last named means to cause it to effect an opening movement of the valve, a second electrical circuit for controlling said last named means to cause it to effect a closing movement of the valve, two electrical contacts arranged to define upper and lower limiting positions of the beam, each'contact being electrically connected with a different one of the two electrical circuits, and a contact on the beam arranged to float normally between the first mentioned contacts and adapted to effect energization of either one or the other of the two electrical circuits upon contacting with either one or the other of the first mentioned contacts, depending upon the direction of unbalance of the beam, so as to reestablish the balance of the beam and of the quantiT ties of fuel and air delivered to the furnace.

3. In a regulating mechanism for maintaining a balanced condition between the quantities of fuel and air delivered to a furnace and embodying a beam balanced about a fulcrum by the variable pressures of the fuel and the air, said beam exerting a controlling effect on the pressure of the air delivered to a furnace by relatively small movements of the beam on either side of its balanced position and between limiting positions, the combination of air delivery means for delivering air to a furnace, a fluid actuated prime mover for actuating the air delivery means, a valve for controlling the supply of fluid to the prime mover, electrically operated means connected to the valvefor effecting different degrees of opening and closing of the valve, an electrical circuit for controlling the last named means to cause it to effect an opening movement of the valve, a second electrical circuit for controlling said last named means to cause it to effect a closing movement of the valve, two electrical contacts arranged to define upper and lower limiting positions of the beam, each contact being electrically connected with a different one of the two electrical circuits, a contact on the beam arranged to float normally between the first mentioned contacts and adapted to effect energization of either one or the other of the two electrical circuits upon contacting with either one or the other of the first mentioned cally operated means connected theretoto effect 3 opening of the aforesaid controlling electrical circuits when the predetermined maximum degrees of opening and closing are reached.

4. In a regulating mechanism for maintaining a balanced condition between the quantities of fuel and air delivered to a furnace and embodying a beam balanced about a fulcrum by the variable pressures of the fuel and the air, said beam exerting a controlling effect on the pressure of the air delivered to the furnace by relatively small movements of the beam on either side of its balanced position and between limiting positions, the combination of air delivery means for delivering air to a furnace, a fluid actuated prime mover for actuating the air delivery means, a valve for controlling the supply of fluid to the prime mover, electrically operated rotary means connected to the valve for effecting different degrees of opening and closing of the valve, said electrically operated rotary means having a relatively high rotative speed and being adapted to rotate in either direction, speed reducing means in the connection between the valve and the electrically operated rotary means, an electrical circuitfor controlling the rotary means to cause it to effect an opening movement of the valve, a second electrical circuit for controlling the rotary means to cause it to effect a closing movement of the valve, two electrical contacts arranged to define upper and lower limiting positions of the beam, each contact being electrically connected with a different one of the two electrical circuits, and a contact on the beam arranged, to float normally between the first mentioned contacts and adapted to effect energization of either one or the other of the two electrical circuits upon contacting with either one or the other of the first mentioned contacts, depending upon the direction .of unbalance of the beam. so as to reestablish the balance of the beam and of .the quantities-of fuel and-air delivered to the furnace.

5. In a regulating mechanism for maintaining a balanced condition between the quantities of fuel and air delivered to a furnace and embodying a beam balanced about a fulcrum by the variable pressures of the fuel and the air, said beam exerting a controlling effect on the pressure of the air delivered to the furnace by relatively small movements of the beam on either side of its balanced position and between limiting positions, the combination,of air delivery means for delivering air to a furnace, a fluid actuated prime mover for actuating the air delivery means, a valve for controlling the supply of the valve, a second electrical circuit for controlling the rotary means to cause it to effect a closing movementof the valve, two electrical contacts arranged to define upper and lower limiting positions of the beam, each contact being electrically connected with a difi'erent one of the two electrical circuits, a contact on the beam arranged to float normally between the first mentioned contacts and adapted to 'eflect energization of either one or the other of the two electrical circuits upon contacting with either one'or the other of the first mentioned contacts, depending upon the direction of unbalance of the beam, so as to reestablish the balance of the beam and of the quantities of fuel and air delivered to the furnace, and means to effect cessationof the opening and closing movements of the valve at predetermined maximum degrees of opening and closing, the last named means comprising a pair of normally closed contacts, one in each of the aforesaid controlling electrical circuits, and means actuated by the connection between the valve and the speed reducing means to effect opening of the contacts at the respective predetermined'maximum degrees of opening and closing of the valve.

6. In a regulating mechanism for maintaining a balanced condition between the quantitiesof fuel and air delivered to a furnace and embodying a beam balanced about a fulcrum by the variable pressures of the fuel and the air, said beam exerting a controlling effect on thepressure of the air delivered to a furnace by relatively small movements of the beam on either side of its balanced position and between limiting positions, the combination of means for controlling the delivery of air to a furnace, an electrical circuit for controlling the last named means to cause itto effect an increase in the quantity of air delivered, a second electrical circuit for controlling said last named means to cause it to effect a decrease in the quantity of air delivered, two electrical contacts arranged to define upper and lower limiting positions of the beam, each contact being electrically connected with a different one of the two electrical circuits, a contact on the beam arranged to float normally between the first mentioned either one or the other of the two' electrical circuits upon contacting with either one or the other of the first mentioned contacts, and means to insure definite making and breaking of the contact between the floating contact and one of the first mentioned contacts, comprising an electro-magnet in each of the electrical circuits mounted in a fixed relationship and having a common armature pivoted intermediate the axesof the electro-magnets, the first mentioned contacts being mounted for rotation with the'armature but electrically insulated therefrom, whereby initial making or breaking of the contact between the floating contact and one of the first mentioned contacts with consequent energization or deenergization of-the respective electro-magnet results in the rotation of the armature and the contacts supported thereon in a direction to insure positive making or breaking of the contact.

7. In a' regulating mechanism for maintaining a balanced condition between the quantities of fuel and air delivered toa furnace and embodying a beam balanced about a fulcrum by the variable pressures of the fuel and the air, said beam exerting a controlling effect on the pressure of the air delivered to a furnace by relatively small movements of the beam on either side of its balanced position and between limiting positions, the combination of air delivery means for delivering air to a furnace, a fluid actuated prime mover for actuating the air delivery means, a valve for controlling the supply of fluid to the prime mover, electrically operatedmeans connected to the valve for effecting difi'erent degrees of opening and closing ofv the valve, an

electrical circuit for controlling the last named means to cause it to effect an opening movement of the valve, a second electrical circuit for controlling said last named means to cause it to effect a closing movement of the valve, a third electrical circuit controlling the first named electrical circuit and containing a resistance element adapted to control the speed of operation of the electrically operated means, switching means adapted to short-circuit said resistance element, a fourth electrical circuit controlling the second named electrical circuit and containing aresistance element adapted to control the speed of operation of the electrically operated means, two electrical contacts arranged to define upper and lower limiting positions of the beam, each contact being electrically connected with a different one of the third and fourth electrical circuits, and a contact on the beam arranged to float normally between the first mentioned contacts and adapted to effect energization of either one or the other of the third and fourth electrical circuits upon contacting with either one or the other of the first mentioned contacts, depending upon the direction of unbalance of the beam, so as to reestablish the balance of the beam and of the quantities of fuel and air delivered to the furnace.

8. In a regulating mechanism for maintaining a balanced condition between the quantities of fuel and air delivered to a furnace and embodying a beam balanced about a fulcrum by the variable pressures of the fuel and the air, said beam exerting a controlling effect on the pressure of the air delivered toa furnace by relatively small movements of the beam on either side of its balanced position and between limiting positions, the combination of air delivery means for delivering air to a furnace, a fluid actuated prime mover for actuating the air delivery means, a valve for controlling the supply of fluid to the prime mover, electrically operated means connected to the valve for effecting different degrees of opening and closing of the valve, an electrical circuit for controlling the last named means to cause it to effect an opening movement of the valve, a second electrical circuit, two electrical contacts arranged to define cause it to effect a closing movement of the valve, a third electrical circuit controlling the first named electrical circuit, a fourth electrical circuit controlling the second 'named electrical ciruit, two electrical contacts arranged to define upper and lower limiting positions of the beam,

each contact being electrically connected with a different one of the third and fourth electrical circuits, a contact on the beam arranged to float normally between the first mentioned contacts and adapted to effect energization of either one or they other of the third and fourth electrical circuits upon contacting with either one or the other of the first mentioned contacts, and

means to insure definite making and breaking of the contact between the floating contact and one of the first mentioned contacts, comprising an electro-magnet in each of the third and fourth electrical circuits mounted in a fixed relationship and having a common armature pivoted intermediate the axes of the electro-magnets, the first mentioned contacts being mounted for rotation with the armature but electrically insulated therefrom, whereby initial making or breaking of the contact between the floating contact and one of the first mentioned contacts with consequent energization or deenergization of the respective electro-magnet results in the rotation of the armature and the contact supported thereon in a direction to insure positive making or breaking of the contact, said electromagnets serving also to actuate the first and second electrical circuits upon actuation, of said electro-magnets in the third and fourth electrical circuits.

9. In a regulating mechanism for maintaining a balanced condition between the quantities of fuel and air delivered to a furnace and embodying a beam balanced about a fulcrum by the variable pressures of the fuel and the air, said beam exerting a controlling effect on the pressure of the air delivered to a furnace by relatively small movements of the beam on. either side of its balanced position and between limiting positions, the combination of air delivery means for delivering air we furnace, a flud actuated prime mover for actuating the air delivery means, a valve for controlling the supply of fluid to the prime mover, electrically operated means connected to the valve for effecting different degrees of opening and closing of the valve, anelectrical circuit for controlling the last named means to cause it to effect an opening movement of the valve, a second electrical circuit for controlling said last named means to cause it to effect a closing movement furnace.

, 7 of the valve, a third electrical circuit controlling the first named electrical circuit, a folirth electrical circuit controlling the second named electrical circuit, separate electrically actuated indicating means associated with each of the first and second electrical circuits and adapted to indicate which of the first and second electrical circuits has been actuated, two electrical con tacts arranged to define upper and lower limit- -ing'.positions of the beam, each contact being electrically connected with a different one of the third and fourth electrical circuits, and a contact on the beam arranged to float normally between thefirst mentioned contacts and adapted to effect energization of either one or the other of the third and fourth electrical circuits upon contacting with either one or the other of the first mentioned contacts, depending upon the, direction of unbalance of the beam, so as to reestablish the balance of the beam and of v the quantities of fuel and air delivered to the 10. In a regulating mechanism for maintaining a balanced condition between the quantities of fuel and air delivered to a furnace and embodying a beam balanced about a fulcrum by the variable pressures of the fuel and the air, said beam exerting a controlling effect on the pressure of the air' delivered to a furnace by relatively small movements of the beam on either side of its balanced position and between limiting positions, the combination of means for controlling the delivery of air to a furnace, a normally open electrical circuit for controlling the last named means to cause it to effect an increase in the quantity of air delivered and= normally connected to one pole of a source of electrical energy, a second normally open electrical circuit for controlling said last named means to cause it to effect a decrease in the quantity of air delivered and normally connectedto the same pole of the source of electrical energy, two electrical contacts arranged to define upper and lower limiting positions of the beam, each contact being electrically connected with a different one of the two electrical circuits, and a contact on the beam connected with the other pole of the source of electrical energy, arranged to float normally between the first mentioned contacts, and adapted to effect energization-of either one or the other of the two electrical circuits upon contacting with either one or the other of the first "mentioned contacts.

11. In a regulating mechanism for maintaining a balanced condition between the quantities of fuel and air delivered to a furnaceand embodying a beam balanced about a fulcrum by the variable pressures of the fuel and the air, said beam exerting a controlling effect on the pressure of the air delivered to a furnace by relatively, small movements of the beam on either side of its balanced position and between limiting positions, the combination of means for controlling the delivery of air to a furnace, an electrical circuit for controlling the last named means to cause it to effect an increase in the quantity of air delivered and normally connected to one pole of a source of electrical energy, a second electrical circuit for controlling said last named means to cause it to effect a decrease in the quantity of air, delivered and connected to the same pole of the source of electrical energy, two electrical contacts arranged to define upper and lower limiting positions of the beam, each contact being electrically connected with a dif-- ferent one of the two electrical circuits, a contact on' the beam connected to the other pole of the.sourceof electrical-energy, arranged to fioat normally between the first mentioned contacts, ,and adaptedto effect energization of either one or the other of the two electrical circuits upon contacting with either one or the other of the first mentioned contacts, switching means in the connection between the normally floating contact and the pole of the source of electrical energy to which it is connected, and a manual testing means comprising normally open fourth and fifth contacts, each being connected in parallel with one of the first mentioned pair of contacts, and means to connect either one of the fourth and fifth contacts to a common switch-point, the aforesaid switching means being adapted to transfer the connection of the one pole of the source of electrical energy from its connection with the normally floating contact to the common switch-point.

12. In a regulating mechanism for maintaining a balanced condition between the quantities of fuel and air delivered to a furnace and em bodying a beam balanced about a fulcrum by the variable pressures of the fuel and the Jr, said beam exerting a controlling effect on the pressure of the air delivered to a furnace by relatively small movements of the beam onnormally connected to the same pole of the source of electrical energy, separate electrically actuated indicating means associated with each ofthe electrical circuits, adapted to indicate which of the circuits has been actuated, and connected to one of the poles of a source of electrical energy, two electrical contacts arranged to define upper and lower limiting positions of the beam, each contact ,being electrically connected with a different one of the two electrical circuits, and a contact on the beam connected to the other pole of the source of electrical energy, as compared with the connection, of the electrical circuits, said last .named contact being arranged to float normally between the first mentioned contacts and adapted to effect energization of either one or the other of the two electrical circuits upon contacting with either one or the other of the first mentioned contacts, the energization of one of the electrical circuits causing its respective electrically actuated indicating means to be connected with the other pole of the source of electrical energy as compared with the connection of the electrically actuated indicating means. g

13. In a regulating mechanism for maintaininga balanced condition between the quantities of fuel and air delivered to a furnace and embodying a beam balanced about a fulcrum by the variable pressuresof'the fuel and the air, said beam exerting a controlling effect on the pressure of the air delivered to a furnace by relatively small movements of the beam on either. side of its balanced position and between limiting positions, the combination of air detrical circuit for controlling said last named ling said last named means to cause it to effect livery means for delivering air to a furnace. a fluid actuated prime mover for actuating the air delivery means, a valve for controlling the supply of fluid to the prime mover, electrically. operated means connected to the valve for effecting different degrees of opening and closing of the valve, an electrical circuit for controlling the last named means to cause it to effect an opening movement of the valve, a second elecnormally connected to the same pole of the source of electrical energy, two electrical contacts arranged to define upper and lower limiting positions of the beam, each contact being ,electrically connected with a different one of the third and fourth electrical circuits, a contact on the beam connected with the other pole of the source of electrical energy, arranged tofloat normally'between the first mentioned contacts, and adapted to effect energization of either one or the other of the third and fourth electrical circuits upon contacting with either one or the other of the first mentioned contacts, and an electro-magnet in each of the third and fourth electrical circuits, said electro-magnets serving to actuate the first and second electrical circuits upon actuation of the said electro-magnets in the third and fourth electrical circuits.

14. In combination with a furnace having sep-'- arate pressure delivery means for fuel and for air, air delivery means for supplying air to' the furnace, electrically controlled means for controlling the air delivery means, an electrical circuit for controllingthe last named means to cause it to effect an increase in the quantity of air delivered, a second electrical circuit for controlling said last named means to cause it to effect a decrease in the quantity of air delivered, and a beam balanced about a fulcrum and controlled jointly by the pressures of the fuel and of the air for controlling said electrical circuits, whereby to maintain asubstantially constant ratio between the quantities of fuel and ,air delivered to the furnace.

15, In combination with a furnace having separate pressure delivery means for fuel and for air, air conducting means for conducting air to the furnace, electrically controlled means for controlling the delivery of air to the air conducting means, an electrical circuit for controlling the last named means to cause it to effect an increase in the quantity of air delivered, a second electrical circuit for control- 1'05 9. decrease in the quantity of air delivered, and a beam balanced about a fulcrum and controlled jointly by the pressures of the fuel and the airfor controlling said electrical circuits, whereby to maintain a substantially constant ratio between the quantities of fuel and air delivered to the furnace.

16. In combination with a furnace having separate delivery means for fuel and for air, electrically controlled means for controlling the delivery of air to the furnace, an electrical circuit for controlling the last named-means to cause it to effect an increase in the quantity of air delivered, .asecond electrical circuit for con- I trolling said last named means to cause it to 1:3

eifect a decrease in the quantity of air delivered, and a beam balanced about a fulcrum and controlled jointly by the pressures of the fuel and the air for controlling said electrical circuits, whereby to maintain a substantially constant ratio between the quantities of fuel and air delivered to the furnace.

17. In combination with a furnace having separate pressure delivery means for fuel and for air, air delivery means for supplying air to the furnace, a prime mover for actuating the air delivery means, variable means for controlling the speed of operation of the prime mover, means to control the variable means, means to control thelast named means by actuation of a beam balanced about a fulcrum and controlled jointly by the pressures of the fuel and the air, and means to effect predetermined, maximum and minimum speeds of the prime mover comprising means, operable upon the attainment of predetermined limiting degrees of operation of the aforesaid variable means, to interrupt operation of the means to control the variable means.

18. In combination with a furnace having separate pressure delivery means for fuel and for air, means for delivering air to the furnace,

7 variable means for controlling the speed of operation of the air delivery means, means to control the variable means, means to control the last named means by actuation of a beam balanced about a fulcrum and controlled jointly by the pressures of the fuel and the air, and means to effect predetermined maximum and minimum speeds of operation of the air delivery means comprising means, operable upon the attainment of predetermined limiting degrees of operation of the aforesaid variable means, to

' interrupt operation of the means to control the variable means.

19. In a regulating mechanism for maintaining a balanced condition between the quantities of fuel and air delivered to a furnace and embodying a beam balanced about a fulcrum by the variable pressures of the fuel and the air, said beam exerting a controlling effect on the pressure of the air delivered to a furnace by relatively small movements of the beam on either side of its balanced position, the combination of means for controlling the delivery of air to afurnace, an electrical circuit for controlling the last named means to cause it to effect an increase in the quantity of air delivered, a second electrical circuit for controlling said last named means to cause it to effect a decrease in the quantity of air delivered, and means controlled by the beam to effect energization of either one or the other of the two electrical circuits, depending upon the direction 'of unbalance ofthe beam, so as to reestablish the balance of the beam and of the quantities of fuel and air delivered to the furnace.

20. In combination with a furnace having separate delivery means for fuel and for air,-

means for controlling the delivery of air to the furnace, an electrical circuit for controlling the last named means to cause it to effect an increase in the quantity of air delivered, a second electrical circuit for controlling said last named means to cause it to effect a decrease in the quantity of air delivered, and a beam balanced about .a fulcrum and controlled jointly by the pressures of the fuel and the air for controlling said electrical circuits, whereby to maintain a substantially constant ratio between the quantities of fuel and air delivered to the furnace.

HARRY CAMPBELL GRANT, .ln.

CERTIFICATE OF CORRECTION.

Patent No. l, 976, 680.

October 9, 1934.'

HARRY CAMPBELL GRANT, JR.

It is hereby certified that error appears in the printed'specification of the above numbered patent requiring correctionas follows:- Page 4. line 119, after "through" insert theword wires; page 7, line 19, claimS, strike out the comma two electrical contacts arranged to define" and insert instead for and words controlling said last named means to; and line 66, claim 9, for "flud" read fluid;

and that the said Letters Patent should be read with these. corrections therein that the same may conform to they record of the case in the Patent Office.

Signed and sealed this 13th day of November, A. D. l934.

(Seal) Leslie Frazer Acting Commissioner of Patents.

effect a decrease in the quantity of air delivered, and a beam balanced about a fulcrum and controlled jointly by the pressures of the fuel and the air for controlling said electrical circuits, whereby to maintain a substantially constant ratio between the quantities of fuel and air delivered to the furnace.

17. In combination with a furnace having separate pressure delivery means for fuel and for air, air delivery means for supplying air to the furnace, a prime mover for actuating the air delivery means, variable means for controlling the speed of operation of the prime mover, means to control the variable means, means to control thelast named means by actuation of a beam balanced about a fulcrum and controlled jointly by the pressures of the fuel and the air, and means to effect predetermined, maximum and minimum speeds of the prime mover comprising means, operable upon the attainment of predetermined limiting degrees of operation of the aforesaid variable means, to interrupt operation of the means to control the variable means.

18. In combination with a furnace having separate pressure delivery means for fuel and for air, means for delivering air to the furnace,

7 variable means for controlling the speed of operation of the air delivery means, means to control the variable means, means to control the last named means by actuation of a beam balanced about a fulcrum and controlled jointly by the pressures of the fuel and the air, and means to effect predetermined maximum and minimum speeds of operation of the air delivery means comprising means, operable upon the attainment of predetermined limiting degrees of operation of the aforesaid variable means, to

' interrupt operation of the means to control the variable means.

CERTIFICATE Patent No. l, 976, 680.

19. In a regulating mechanism for maintaining a balanced condition between the quantities of fuel and air delivered to a furnace and embodying a beam balanced about a fulcrum by the variable pressures of the fuel and the air, said beam exerting a controlling effect on the pressure of the air delivered to a furnace by relatively small movements of the beam on either side of its balanced position, the combination of means for controlling the delivery of air to afurnace, an electrical circuit for controlling the last named means to cause it to effect an increase in the quantity of air delivered, a second electrical circuit for controlling said last named means to cause it to effect a decrease in the quantity of air delivered, and means controlled by the beam to effect energization of either one or the other of the two electrical circuits, depending upon the direction 'of unbalance ofthe beam, so as to reestablish the balance of the beam and of the quantities of fuel and air delivered to the furnace.

20. In combination with a furnace having separate delivery means for fuel and for air,- means for controlling the delivery of air to the furnace, an electrical circuit for controlling the last named means to cause it to effect an increase in the quantity of air delivered, a second electrical circuit for controlling said last named means to cause it to effect a decrease in the quantity of air delivered, and a beam balanced about .a fulcrum and controlled jointly by the pressures of the fuel and the air for controlling said electrical circuits, whereby to maintain a substantially constant ratio between the quantities of fuel and air delivered to the furnace.

HARRY CAMPBELL GRANT, .ln.

0F CORRECTION.

October @1934;

HARRY CAMPBELL GRANT, JR.

It is hereby certified that error appears in the printed'speciiication of the above numbered patent requiring correctionas follows:- Page 4. line 119, after "through" insert theword wires; page 7, line 19, claimS, strike out the comma and words two electrical contacts arranged to define" and insert instead for controlling said last named means to; and line 66, claim 9, for "flud" read fluid; and that the said Letters Patent should be read with these. corrections therein that the same may conform to they record of Signed and sealed this 13th day of (Seal) the case in the Patent Office. November, A. D. l934.

Leslie Frazer Acting Commissioner of Patents. 

